I got mine through accurate suspension but if you can live with a longer spring there is an awesome site to get them cheap from.
http://www.otomoto.com.au/HDSystems/sleevekits.htm$300 with springs and a spanner is an awesome price, Usually looking to pay $250 for sleeves and seats and another $250 for the springs. For the front of a street 1200 a 4kg spring is awesome.